1. Field of the Invention
This invention relates to a camera which is capable of recording information designating a trimming range at the time of photographing.
2. Related Background Art
Cameras which can be used for trimming shots are already well known (see, for example, Japanese Patent Publication No. 61-43698). In a trimming shot, information designating the trimming range is recorded at the time of photographing so that only the designated range of the image taken will be printed on photographic paper in the printing process after the development of the film. Thus, what is obtained by printing is a trimmed picture representing a part of the shot image in an enlarged form.
Generally, the optical system of a camera photographic lens is so designed that its optical performance (including, for example, the MTF (modulation transfer function) and aberration) allow a satisfactory image to be obtained uniformly over the entire area of the shot image. However, as is generally known, optimum images of a subject are formed at different positions in the direction of the optical axis for different heights of the image above the optical axis, so that the optimum image field obtained by an image-forming luminous flux around the optical axis generally differs from that obtained by a peripheral image-forming luminous flux.
When, as in a trimming shot, only a portion of an image is to be printed, image optimization presents a problem. More particularly, depending on the location of the image portion to be printed (for example, an image portion whose height Y above the optical axis is approximately 0 versus one whose height Y above the optical axis is approximately 20 mm), there may or may not be a correspondence with the optimum image portion in the overall photographic image.
In addition, when printing trimming-shot images, the enlarging magnification is higher than in normal shots, where the entire shot image is printed on photographic paper. As a result, the quality of a trimming-shot image is inevitably inferior to that of a normal-shot image. Thus, a trimming shot is quite likely to fail to provide an optimum image which would surely have been obtained by a normal shot, although better optical performance of the photographic lens is desired therefor.
The problems with the relevant prior art will be further discussed. The photographic apparatus disclosed in the above-mentioned reference, Japanese Patent Publication No. 61-43698, is equipped with a finder optical system which makes it possible to set a trimming range in correspondence with the visual field of the finder. A trimming-control means which is coupled with the finder optical system drives a trimming-information recording device, thereby recording the trimming magnification corresponding to the visual field of the finder.
In the above-described prior art, the print enlarging magnification for a trimming shot is higher than that for a normal shot (the magnification corresponding to a standard print size, for example, the "service size"), so that a deterioration in the quality of the peripheral image portions that would constitute no particular problem in a normal shot may be conspicuous in a trimming shot.
The enlarging magnification designated is the same whether the trimming is to be effected in the middle of an image or in a peripheral area thereof as long as the image size is the same. This is in particular a problem where trimming is effected in a peripheral image area because a satisfactory image quality is often not obtained there. In order that a satisfactory image quality may be secured, it has been proposed that the lens aperture be controlled at the time of photographing. This, however, involves changes in the out-of-focus effect, so that the image as intended by the photographer cannot be obtained.